ecryptfs: initialize new auth_tokens before teardown

ecryptfs_destroy_mount_crypt_stat() checks whether each
auth_tok->global_auth_tok_key is nonzero and if so puts that key.  However,
in some early mount error paths nothing has initialized the pointer, and we
try to key_put() garbage.  Running the bad cipher tests in the testsuite
exposes this, and it's happy with the following change.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Cc: Michael Halcrow <mhalcrow@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/ecryptfs/keystore.c

@@ -1860,7 +1860,7 @@ ecryptfs_add_global_auth_tok(struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
 	struct ecryptfs_global_auth_tok *new_auth_tok;
 	int rc = 0;
 
-	new_auth_tok = kmem_cache_alloc(ecryptfs_global_auth_tok_cache,
+	new_auth_tok = kmem_cache_zalloc(ecryptfs_global_auth_tok_cache,
 					GFP_KERNEL);
 	if (!new_auth_tok) {
 		rc = -ENOMEM;